A scanning transmission electron microscope (STEM), a transmission electron microscope (TEM), or the like is used to observe the internal structure of an object in a minute region of the object. As a general observation method for observing the inside of a specimen with use of such an electronic microscope, known is arranging, on a mesh specimen base that includes multiple holes, a specimen that is thinly sliced to the extent allowing transmission of an electronic beam and acquiring a transmitted electron beam at a detector that is arranged on the opposite side of a specimen surface from an electron source side. Furthermore, as a method for three-dimensionally observing the internal structure of an object, a method for acquiring transmission electron microscope images in various azimuths by inclining a specimen has recently drawn attention in the field of material, medical science, and biology. In PTL 1, suggested is a method for finding three-dimensional positional arrangement by inclining a specimen.
The internal structure of an object can be observed with not only the electronic microscope but also an optical microscope. Using the optical microscope allows acquisition of color information that cannot be acquired with the electronic microscope. As a specimen preparation method for optical microscopic observation, widely used is, for example, a method of placing a specimen thin enough for transmission of light or thinly applying a liquid-state specimen on a flat base such as a slide glass and observing the specimen.